JPS6055865B2 - Optical reader for barcodes and labels - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to optical scanning systems, and more particularly to an optical reader for barcode labels located on the interior surface of a cylindrical tube.

Automatic reading of barcode labels located on the interior surface of cylindrical yarn tubes is necessary in many mechanical textile packaging processing systems.

An example of an apparatus for scanning a bar code label placed on the interior surface of an open-ended tube is disclosed by Herrin in US Pat. No. 3,931,524. This device must be moved into contact with the tube so that the encoded record can be read. If the tube mating and device loading and unloading operations can be omitted, the reading process can be speeded up and the possibility of scan contamination by tube debris can be reduced. Furthermore, in practice some labels may not be placed parallel to the tube end, but it may be preferable to scan the inside of the tube at many angles. It is an object of the present invention to read a barcode label affixed to the internal surface of an open-ended cylindrical tube without inserting any part of the reading device into the tube and without requiring precise positioning of the label within the tube. The object of the present invention is to provide a device capable of scanning. A special embodiment of the device has an optical axis approximately coincident with the longitudinal axis of the tube, a wide-angle lens at a distance from the tube but very close to it, and a field at a distance from the wide-angle lens but coaxial. (Field)
It consists of a lens, a tube, and means for producing a slightly convergent beam of light at a distance from the optical axis and for directing the beam in a path substantially parallel to the optical axis. The device further includes a first light beam deflector placed in the optical path for receiving light and deflecting the light in the optical axis direction, and a field lens that receives light from the first light beam deflector and directs the light to the field lens. a second optical beam deflector centered on the optical axis for reflection in the direction of the optical axis; The first and second deflectors are shaped approximately sinusoidally by controlling the phase to mutually deflect the beam along a second path that extends from the optical axis and rotates about it as it approaches the field lens. Means for vibrating is provided. A photodetector is placed between the wide-angle lens and the tube on the optical axis to receive light reflected from a barcode label placed on the interior surface of the tube. A signal decoder is coupled to the photodetector for comparing detected relative bar widths and spacings of the bar code label. The invention will now be described in detail with reference to additional drawings.

Referring to FIG. 1, the apparatus generally includes an optical unit 14 connected to a decoding unit 16 via a cable 18.

The optical unit has a barcode label 12 on its internal surface.
The open-ended tube 10 with attached tube 10 is shown in position to be scanned through the window 20. Figure 2 shows the optical unit 1
4 in more detail, the tube 10 with its label 12 has its longitudinal axis 11 aligned with the wide-angle lens 2.
2 (e.g. MirlOltaROkkOr-Xl6l
glI. ×F2.2) and an associated coaxial field (Field) lens 22 located below the window 20 and centered with respect to the window 20 to approximately coincide with the optical axis 26.

A means for producing a slightly convergent beam of light 28 is a laser tube 30 (e.g. model 3203H-COl).
HUgtleSAircraftCO. ) and its converging lens 32 which directs the beam 28 in a path substantially parallel to the optical axes of the field lens systems 22, 24. A first optical beam deflector 34 is placed in the path of the optical beam 28 from the laser tube 30 to deflect the beam from its initial path to the optical axis 26, and a second optical beam deflector 36 is placed in the path of the optical beam 28 from the laser tube 30 to deflect the beam from its initial path to the optical axis 26. and reflects the light beam along a second path, so that the light beam passes through the field lens 24.
The light beam diverges from the optical axis 26 at an angle θ and rotates about the axis so as to pass through the wide-angle lens 22 and the window 20 to the interior surface of the tube 10. Finally, the photodetector 38 (e.g. United modified to 0.125I cap height)
DetectOrTechnOlOgyUDT#6D)
is placed between the lens 22 and the tube 10 on the optical axis 26. The detector is mounted on a glass window 20 so that the laser beam 28 can be scanned around the detector without obstruction. This is a transparent conductor lead 21 on a glass window 20.
This can be achieved by using The glass is square (
It has on its surface a conductive transparent tin oxide coating with a resistance of 20 to 300 ohms per square. The coated portion is etched with a heterogeneous mixture of hydrochloric acid and zinc powder to form the portion of the lead 21 connected to the detector. Lead 21 connects the detector to a preamplifier 40, which in turn is connected to a discrimination circuit 42. The optical beam deflectors 34, 36 are mirrors driven relative to respective galvanometer motors 34a and 36a, which motors are driven by signals from amplifiers 23 and 35, respectively.

Typically the light beam deflector is a GelleralSca
nningIr)C. Motor Model G-115 with M-2-1010-00 mirror and 10B mount. The signal is transmitted almost sinusoidally to the mirrors 34 and 36 in relation to position control.
vibrate. This word “゜almost sinusoidally” means
The oscillations from amplifiers 33 and 35 are not of the same amplitude but are 90 degrees out of phase with each other, causing the beam 28 to follow a circle inside the tube 10, and where the oscillations are not of the same magnitude, an ellipse follows the field lens surface. Contains.
If the amplitude ratio of the vibrations is constant but the amplitude varies, the trace pattern of the beam 28 moves helically up and down the tube. This scanning pattern covers most conditions of normal label position. However, highly skewed or distorted labels cannot be completely scanned without additional scanning control.
If, in addition to the latter condition, the amplitude ratio also changes, a continuously varying elliptical trace can be generated that projects into many scan angles within the yarn tube. Finally, if we impose a phase delay change on the two vibrations from 33 and 35, the trace will also process near the inside of the tube. In this approach, the beam scans highly oblique labels as well as normally placed labels. Means for providing these approximately sinusoidal signals are discussed below. For example, in FIG.
rchCOrp. NO. BB-4423) is multiplier 5
an amplifier 35 connected to 4 and which in turn drives mirror 36;
The phase shifter 55 is connected to the phase shifter 55 which is connected to the phase shifter 55 . Similarly, the oscillator 52 (BB-4423) is connected to the multiplier 54 (eg, B-4423).
frBrOwnCOrp. The multiplier 54 is connected to the amplifier 33 which drives the mirror 34. In operation of this circuit, a sine signal from oscillator 50 is multiplied by a triangular wave signal generated by oscillator 52 in multiplier 54 . As a result, the amplitude of the sine wave changes at a constant ratio between the two boundary amplitudes. The modulated sine wave is then phase shifted by phase shifter 55 and then amplified to drive mirror 36. On the other hand, the phase-invariant signal from multiplier 54 is amplified to drive mirror 34. In operation, the scanner (Scan
rler) utilizes mirrors 34, 36 and associated wide-angle lens 22 with their field lens 24 to generate a circular pattern of laser light focused onto a small spot on the interior surface of tube 10 by helical scanning. . More specifically, a helical scan is obtained by sinusoidally oscillating mirrors 34 and 36 each 900 degrees out of phase while slowly varying the amplitudes of both sinusoids simultaneously. The latter action generates a circle according to the well-known Lissage principle,
The former action slowly changes the diameter of the circle. The result is a helical scan within the tube. It is important that a phase shift of approximately 90° is maintained between the sinusoidal movements of the two mirrors while the amplitude of the sine wave changes. As the scan passes over the barcode label 12, the change in reflection between the bar 12a and the space 12b is detected by a photodetector 3' installed on the surface of the window 20 and converted into a signal which is sent to the preamplifier. 4
0 and then converted into a digital signal by a discriminator 42. This digital signal represents a label code where a 0 volt signal level corresponds to white or space and +2 volts corresponds to black or bar. The width of the signal is proportional to the width of the bars and spaces. Next, the digital signal is cable 18
to a decoder such as that used with the ACCUSOrt55OO moving beam scanner in the MRC-8000 Series Scanner 1 decoder. The mathematical representation of the electrical drive signal from the apparatus of FIG. 4 used to scan the diagonal label is as follows.

The signal x<5y that generates the ellipse processing pattern is: L(
1) X(t) = ACOSWltCOSW2t-BSin
WltSinW2t(2)y(t)=ACOSWltS
inW2t+BSinWltCOSW2t where W1:
Scanning frequency W2: Precession frequencies (4) and (B) are constants proportional to the lengths of the larger and smaller axes of the precession ellipse.

The means for providing these signals will be described in connection with FIG.

Equations (1) and (2) can also be written as follows. (3) x(t
)=m1[Nl2cOswltcOsw2t) -Si
nWlLSinW2t] (4) y(t)=m1[Nl2cOswltsinw2
t+SinwltcOsw2t] Here, (m1) is a proportionality constant that determines the overall size of the ellipse, and (M2) is a constant that determines the scanning angle by controlling the shape of the ellipse.

It is equal to the ratio of the lengths of the axes of the ellipse (i.e. j = A/B
).

In order to automatically scan at different angles and depths of the tube, the constants (m1) and (Rn2) must be varied with time.

If (m1) and (M2) are functions of time, the equation becomes as follows. (5)x(t)=m1(t)[n)2(t)
COSWltCOSW2t-SinWltSinW2t
](6)y(t)=m1(t)[Nl2(t)COSW
ltSinW2t+SinwltcOsw2t] The modulation functions m1(t) and Rn2(t) are selected depending on the type of label and tube being scanned.

Oscillators 60 and 62 (Burr-BrOwnMOdel4
423) are the scanning frequency (W,) and the precession frequency (W2)
generate the sine and cosine terms of .

The amplitude of the term COswlt is determined by the addition circuit 63 (TexasIr
Function M2 from lStrl]MentTLO83CN)
(t) multiplier circuit 61 (Burr-BrOwn42
O'3J) to change the scan angle. The modulation function M2(t) is the sum of the DC voltage from the adjustable DC voltage source 64 that sets the initial scan angle and the periodic component from the signal generator 65 that changes the scan angle around the set point. The sine and cosine terms generated by the oscillator are: are multiplied by multipliers 66, 67, 68, and 69, and the terms shown below are formed by these arrangements.

The signal from 66 is sent to subtraction circuit 70 (TexasIrlSt
rLlmentTLO83CN) from the signal from 67.

The signals at the outputs of multipliers 68 and 69 are summed in adder circuit 71. The amplitude of the signals at 70 and 71 is modulated by a function m1(t) to vary the scanning depth.

The modulation function m1(t) consists of a periodic component that changes the initial tube scan depth around its set point and an x voltage that sets the initial tube scan depth, i.e., a signal generator that is combined in a summing circuit 78. 73 and the adjustable power supply 72. The signals at multipliers 74, 75 result from depth modulation. Before being sent to the ゜゜x゛ and ゜y゛ galvanometers, these signals are passed through an amplifier 76 to increase their power.
, 77 (NatiOrkllSemiconductO
rLHOO2l). These signals are fed directly to the ``゜x゛'' and ゜゜y゛ galvanometers 34a, 36a. The galvanometer mirrors 34, 36 are generally capable of approximately sinusoidal oscillation. Therefore, the shape of the trace It is important that the changes in the time-dependent constants m1 and M2 are continuous and gradual even if there is a decrease in magnitude or angle.The equation representing the output signal of each element is as follows: be.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the apparatus of the invention for a yarn tube. FIG. 2 is a simplified diagram of the optical portion of the device including the photodetector associated with the yarn tube. FIG. 3 is a block diagram of a drive circuit for vibrating the mirror shown in FIG. 2. Figure 4 is the second
Another drive circuit for vibrating the mirror shown in the figure. 10;
Tube, 12; Barcode label, 22: Wide-angle lens, 24; Field lens, 26; Optical axis, 28
; light beam, 34; first light beam deflector, 36; second light beam deflector, 38; photodetector.

Claims (1)

Claims: 1. An apparatus for scanning a light-reflecting barcode label 12 disposed on the interior surface of a tube 10 and providing an encoded signal; with a wide-angle lens 22 having an optical axis 26;
a wide-angle lens disposed in close proximity to the tube, the optical axis and the longitudinal axis of the tube substantially coinciding;
A field lens 24 that is a little apart from the wide-angle lens 22 and coaxial with it; generates a slightly convergent light beam 28 at a position a little distance from the tube 10 and the optical axis, and directs the beam into a path almost parallel to the optical axis. Directing means 30, 32
and; a first optical beam deflector 3 disposed in the path for receiving the optical beam 28 and deflecting it from the path in the direction of the optical axis 26.
4; the optical axis 2 for receiving the light from the first light beam deflector and reflecting it towards the field lens 24 so that all the light is received by the field lens 24;
6 a centrally placed second optical beam deflector 36; for mutually deflecting the beams along a second path extending from the optical axis 26 and rotating about it as it approaches the field lens 24; , means 33, 34a, 35, 36a for vibrating the first deflector and the second deflector 34, 36 substantially sinusoidally in a phase-controlled relationship; a bar disposed on the inner surface of the tube 10; for receiving light reflected from code label 12 and providing an encoded signal;
the wide-angle lens 22 and the tube 10 on the optical axis 26;
and a photodetector 38 interposed therebetween. 2. The device according to claim 1, wherein the wide-angle lens 22 is a fisheye lens. 3. Device according to claim 1, characterized in that said means for generating a slightly convergent light beam comprises a laser tube (30) and a convergent lens (32). 4. The apparatus of claim 1, further comprising a signal decoder (16) coupled to the optical deflector (38).